The present invention relates to veneer-slicing apparatus, and, more particularly, to a veneer-slicing apparatus of the type described in U.S. Pat. Nos. 793,306; 2,576,520; and 3,441,069 wherein a log section or flitch is mounted on a reciprocating flitch table adjacent a cutting blade which is positioned to slice a veneer sheet from the flitch during each reciprocation of the flitch table. The cutting blade is mounted on a movable carriage which is indexed forwardly toward the flitch after each reciprocation of the flitch table. The apparatus advances and properly positions the cutting blade relative to the flitch for slicing successive veneer sheets therefrom.
The apparatus described in the above-referenced patents is large and massive. Such apparatus weighs several tons in addition to the flitch weight, and yet must be capable of slicing veneer sheets having a uniform thickness of 0.02 inch or less with accuracy and at a high rate of speed. This requires that the apparatus be accurately adjusted prior to initiation of a slicing operation and that it be precisely controlled during the slicing operation.
For example, one adjustment that must be performed prior to initiation of a slicing operation is to position a pressure plate with respect to the edge of the cutting blade. More specifically, if the apparatus is designed to slice a veneer sheet from the flitch during each downward stroke of the reciprocating flitch table, the pressure plate will be positioned above and behind the edge of the cutting blade to define a narrow space or blade opening between the cutting blade and the pressure plate through which the veneer sheet passes as it is sliced from the flitch. The veneer sheet is then received by a transport assembly which transfers the sheet to a location to be picked up by an operator. The pressure plate provides support for the veneer sheet as it is being sliced; and in order to produce a high-quality sheet of uniform thickness, it must be accurately positioned with respect to the cutting edge of the blade.
The pressure plate is mounted to a pressure plate support means which, in turn, has a large feed screw at each end thereof. In current systems, adjustment of the horizontal position of the plate is accomplished by manually rotating the two screws with a large wrench, causing the ends of the pressure plate support means and the pressure plate mounted thereto to move forward or backward; and an operator must move back and forth from one side of the apparatus to the other, checking the alignment of the pressure plate and blade edge by hand upon each rotation of the screws until he is satisfied that the pressure plate and blade edge are properly positioned relative to one another across the entire several foot length of the blade.
It is difficult to move the pressure plate by the very small and precise amounts needed for accurate positioning. Thus, the procedure tends to be somewhat time consuming and to require an operator of substantial skill.
As indicated above, the cutting blade typically slices a veneer sheet from the flitch during each downward stroke of the flitch table. Following each such stroke, the flitch table must be returned to its uppermost position in preparation for slicing the next sheet from the flitch. In order to insure that the flitch will not contact and possibly damage the cutting blade during the upward movement of the flitch table, it is necessary to move the cutting blade back and out of the way of the flitch. In current systems, this is done by mounting an assembly consisting of the blade holder and pressure plate support member on ball joints for pivotal movement relative to the flitch table. Before each upward stroke of the flitch table, the assembly is caused to pivot back out of the way of the flitch and, thereafter, to pivot back into a vertical position for slicing the next sheet.
The apparatus is designed to slice up to 150 veneer sheets per minute, and the resulting rapid oscillation of the massive pressure plate and cutting blade assembly places a substantial strain on the equipment. Furthermore, it is frequently necessary to change the setting of the blade and pressure plate in changing from one flitch to another, particularly if the flitches are of different woods.
The pressure plate and cutting blade assembly is supported on a movable carriage; and after each sheet is sliced from the flitch, the carriage must be stepped forward to position the blade relative to the flitch for slicing the next sheet. Each step is quite small, e.g., 0.02 inch, and is currently accomplished by a complex system of gears and other mechanical components connected to the drive motor for the reciprocating flitch table.
Frequently, during the operation of the apparatus, it becomes necessary to stop the system for one reason or another. For example, the apparatus might jam; a flitch might fall off of the flitch table; or the flitch may have a nail or other foreign object embedded therein which must be removed to avoid damaging the cutting blade. In such circumstances, the apparatus must be stopped; and the carriage must be moved away from the flitch table for servicing.
After servicing is completed, the carriage must be returned to the correct position to continue the slicing operation; and currently, this is a relatively time-consuming operation which significantly increases the downtime of the apparatus.